function figure_linearcorrelation()
    numpoints = 200;    
    x1=randint(1,numpoints,[-200,200]);
    y1=randint(1,numpoints,[-200,200]);
    z1=x1*2-y1+80;
    d4=randint(1,numpoints,[-200,200]);
    d5=randint(1,numpoints,[-200,200]);
    d6=randint(1,numpoints,[-200,200]);
    data = [x1',d4',d5', y1',z1',d6'];
    save('figure_linearcorrelation.mat','data');
    [x,y] = meshgrid(-200:400:200);
    z = x*2-y+80-1;
    surf(x,y,z,'FaceColor','cyan','FaceAlpha',0.5);
    hold on;
    plot3(x1,y1,z1,'r.');
    grid on;
    hold on;
end
